Automate upgrade stop planning process

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Current process

1. raise issue to collect requirements from all development teams for a potential upgrade stop
2. announcement internally to ensure that everyone is aware which stop to target
3. raise issue for Gitlab::Database::MIN_SCHEMA_GITLAB_VERSION in the release following the required stop
4. File an issue with the Database group to squash migrations to that version in the next release. (Details on Step 3)
5. create issue for Upgrade path in https://gitlab.com/gitlab-com/support/toolbox/upgrade-path